Hybrid Powertrain Gearbox Torque Shift Control
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Solution Overview
Problem
Hybrid powertrains face challenges in achieving desired gear shifts with a small number of gear steps without torque interruption, often requiring complex and heavy clutch mechanisms that increase fuel consumption and wear, and limiting the compactness and reliability of the drive arrangement.
Innovation Solution
A method involving a gearbox with two planetary gears and two electrical machines, where coupling devices and locking mechanisms allow for synchronous rotational speeds between planetary wheel carriers and sun wheels, enabling gear shifts without torque interruption and reducing the need for conventional clutches, resulting in a compact, reliable, and efficient powertrain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional clutch mechanisms are used to achieve gear shifts, then gear shifting is possible, but the device complexity increases, weight increases, and fuel consumption increases
Solution Approach 1:
The patent extracts and eliminates the conventional clutch mechanism from the hybrid powertrain. By using the planetary gear set's inherent ability to disconnect torque flow through controlled engagement of clutch elements (C1, C2, C3) and braking elements (B1, B2, B3), the system achieves gear shifting without requiring a separate clutch device, thereby reducing device complexity and weight
Solution Approach 2:
The planetary gear set is designed to perform multiple functions: it provides gear ratio changes, enables torque interruption during shifts, and allows for different operating modes (electric motor-only, combustion engine-only, or combined). This multi-functionality eliminates the need for dedicated clutch mechanisms, reducing overall system complexity while maintaining ease of operation
2Ease of operation
If conventional clutch mechanisms are used to achieve gear shifts, then gear shifting is possible, but weight increases and cost increases
Solution Approach 1:
The patent removes the separate clutch mechanism from the powertrain architecture. The gear shifting function is achieved through the planetary gear set's internal clutch and brake elements, which are already necessary for mode transitions. This extraction eliminates redundant components, reducing powertrain weight
Solution Approach 2:
The patent merges the gear shifting function with the existing planetary gear set operations. The same clutch elements (C1, C2, C3) and brake elements (B1, B2, B3) that manage torque distribution between the electric motor and combustion engine are also used for gear shifting. This consolidation eliminates the need for additional clutch components, reducing weight and cost
3Ease of operation
If conventional clutch mechanisms are used to achieve gear shifts, then gear shifting is possible, but fuel consumption increases due to wear and heating
Solution Approach 1:
The patent replaces the friction-based conventional clutch mechanism with a planetary gear-based torque management system. The clutch elements (C1, C2, C3) and brake elements (B1, B2, B3) in the planetary gear set provide torque interruption through mechanical engagement rather than friction, significantly reducing energy loss due to heating and wear
Solution Approach 2:
The patent enables continuous torque flow through the planetary gear set during gear transitions. By carefully controlling the engagement sequence of clutch and brake elements, the system maintains torque transmission without interruption or significant energy loss, unlike conventional clutches that require friction-based sliding during engagement
4Device complexity
If the number of gear steps is reduced, then the device complexity decreases, but the adaptability decreases
Solution Approach 1:
The patent adds a new dimension to gear ratio adjustment by incorporating an electric motor with variable speed capability. Instead of relying solely on multiple fixed gear steps, the system can continuously adjust the effective gear ratio by varying the electric motor's rotational speed, thereby achieving the same adaptability with fewer mechanical gear steps
Solution Approach 2:
The patent introduces dynamic gear ratio adjustment through the electric motor's variable speed operation. The effective gear ratio becomes a dynamic parameter that can be continuously adjusted by controlling the electric motor's speed, rather than being fixed at discrete steps. This dynamic approach maintains adaptability while reducing the number of mechanical gear components
Data Source
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AI summary
The present invention relates to a method to control a hybrid powertrain (3), comprising a combustion engine (4); a gearbox with an input shaft (8) and an output shaft (20), which combustion engine is connected to the input shaft (8); a first planetary gear (10), which is connected to the input shaft (8): a second planetary gear (12), connected to the first planetary gear (10); a first electrical machine (14), connected to the first planetary gear (10); a second electrical machine (16), connected to the second planetary gear (12); at least one gear pair (Gl, 60, 72), connected with the first planetary gear (10) and the output shaft (20); and at least one gear pair (G2, 66, 78), connected with the second planetary gear (12) and the output shaft (20). The method comprises the steps: a) engaging gears in the gearbox (2), corresponding to the at least one gear pair (Gl, 60, 72), which is connected with the first planetary gear (10), and to the gear pair (G2, 66, 78), which is connected with the second planetary gear (12) and the output shaft (20); and b) connecting two rotatable components (28, 32, 51) in the second planetary gear (12) with a second coupling device (58). The invention also relates to a vehicle (1) with a hybrid drive line (3), which vehicle (1) comprises a gearbox (2), which is controlled according to the method. The invention also relates to a computer program (P) to control a hybrid powertrain (3) and a computer program product comprising program code for an elec- tronic control device (48) or another computer (53) to implement the method according to the invention.