Torque Overlay Device for Hybrid Drive Systems
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Solution Overview
Problem
Current hybrid drive systems face inefficiencies due to suboptimal operation of both internal combustion engines and electric motors, leading to performance and energy disadvantages, along with complex installation requirements and unnecessary energy losses.
Innovation Solution
A torque superimposition device with a first and second transmission device, each comprising planetary and spur gear sets, allowing independent gear ratio selection for both motors, optimizing their operating points and reducing energy losses through efficient torque summation at the output, thereby enhancing energy efficiency and compactness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the electric motor and combustion engine are coupled in front of the transmission in a hybrid parallel architecture, then both drive units can be operated in the same gear, but the electric motor is operated at a non-optimal operating point resulting in performance and energy disadvantages
Solution Approach 1:
The transmission system is segmented into two independent transmission devices: a first transmission device for the electric motor and a second transmission device for the combustion engine. Each transmission device can be independently controlled to provide optimal gear ratios for their respective drive units, allowing both motors to operate at their optimal operating points while maintaining a relatively simple overall structure.
2Adaptability or versatility
If power splitting of the drive torque is implemented, then two electric motors can be used with one as generator and one as motor, but energy losses occur as a result of the power split
Solution Approach 1:
The invention extracts the torque summation point from the input side and moves it to the output side of the transmission devices. This allows each transmission device to operate independently without power splitting losses, as the torques are combined after transmission rather than before, eliminating the energy losses associated with power splitting while maintaining operating mode flexibility.
3Use of energy by moving object
If a hybrid drive with separate transmission devices for electric motor and combustion engine is used, then both drive units can be operated at optimal points, but the installation space requirement increases
Solution Approach 1:
The invention merges the two separate transmission devices into a compact integrated structure where the first transmission device for the electric motor and the second transmission device for the combustion engine are arranged in close proximity and share common components. This merging approach allows both drive units to operate at optimal points while minimizing the overall installation space requirement.
4Reliability
If total power is required during shifting processes, then tractive force continuity is needed, but the complex topology affects performance
Solution Approach 1:
The invention implements dynamic control of the transmission stage selection based on the current operating conditions and power requirements. During shifting processes, the system dynamically adjusts the gear ratios of both transmission devices to maintain tractive force continuity and total power output, while the simplified topology enables faster and more reliable shifting compared to complex alternative designs.
Data Source
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AI summary
The invention relates to a torque overlay device for use in a hybrid drive system (1) for motor vehicles, and particularly for use in passenger vehicles, said hybrid drive system (1) comprising an internal combustion engine (VM), an electric motor (EM) and the torque overlay device, and a torque of the internal combustion engine (VM) and a torque of the electric motor (EM) being able to be overlaid using said torque overlay device. The torque overlay device is connected, on the output side, to a driven element (9) of the vehicle, and comprises a first and a second torque input (3, 4) and a torque output (5), as well as a first transmission device (12) and a second transmission device (13). Said electric motor (EM) can be coupled to the first torque input (3) in a torque-resistant manner, and the internal combustion engine (VM) can be coupled to the second torque input (4) in a torque-resistant manner, said first torque input (3) being connected to the first transmission device (12) and the second torque input (4) being connected to the second transmission device (13), both in a torque-resistant manner, and said transmission devices (12, 13) each being coupled, on the driven side, to the torque output (5) of the torque overlay device in a torque-resistant manner. The first transmission device (12) comprises at least two alternately selectable transmission stages (EM1, EM2) and the second transmission device (13) comprises at least one alternately selectable transmission stage (VM3, VM4), said first transmission device (12) comprising at least one planetary gear set (15) to implement the at least two alternately selectable transmission stages (EM1, EM2), and the second transmission device (13) comprising at least one spur gear set (27, 28) to implement the at least one selectable transmission stage (VM3, VM4). The invention also relates to a hybrid drive system (1) comprising a torque overlay device of the aforementioned type, as well as to a method for operating such a hybrid drive system (1) in a motor vehicle.