Parallel Drivetrains for Hybrid Motor Vehicle Drive Space Reduction
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Solution Overview
Problem
Large electromechanical energy converters required for hybrid vehicle drives occupy excessive space, while smaller ones are limited in power and speed, making them inadequate for efficient torque transmission across various driving conditions.
Innovation Solution
A motor vehicle drive device with two parallel drivetrains, one featuring a starter generator transmission with a step-down ratio and a one-way clutch for increased torque at startup, and another with a speed-sensitive centrifugal clutch for bidirectional torque transmission at higher speeds, utilizing a small-sized electromechanical energy converter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a large electromechanical energy converter is used, then sufficient torque and power are available for hybrid drive operations, but installation space requirements increase excessively
Solution Approach 1:
The drivetrain is segmented into two parallel drivetrains with different functional characteristics. The first drivetrain handles low-speed high-torque operations (engine starting) while the second drivetrain handles high-speed operations (vehicle driving). This segmentation allows each drivetrain to be optimized for its specific operating range, enabling the use of a smaller electromechanical energy converter that would not need to provide maximum torque across the entire speed range.
Solution Approach 2:
The system dynamically switches between two drivetrains based on operating conditions. The first drivetrain with step-down ratio is engaged for engine starting, while the second drivetrain with 1:1 ratio is engaged for vehicle driving. This dynamic switching allows the electromechanical energy converter to operate at optimal points in different operating modes, reducing the required size while maintaining performance.
2Area of stationary object
If a small electromechanical energy converter is used to reduce installation space, then space requirements are reduced, but torque transmission capability is limited at various speeds
Solution Approach 1:
The first drivetrain acts as an intermediary mechanism that provides torque multiplication through its step-down ratio during engine starting operations. This allows a smaller electromechanical energy converter to produce sufficient starting torque by mechanically amplifying its output through the transmission ratio, rather than requiring the converter itself to generate high torque directly.
3Force
If a single drivetrain with step-down ratio is used for torque multiplication, then starting torque is improved, but torque transmission efficiency decreases at higher speeds
Solution Approach 1:
The system dynamically selects which drivetrain to engage based on speed requirements. At low speeds during engine starting, the first drivetrain with step-down ratio is engaged to provide torque multiplication. At higher speeds during vehicle driving, the system switches to the second drivetrain with 1:1 ratio to minimize energy losses and improve transmission efficiency. This dynamic adaptation resolves the contradiction between needing high starting torque and maintaining efficiency at operating speeds.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables efficient hybrid drive systems with sufficient torque at low and high speeds, reducing installation space requirements while maintaining drive performance across the entire speed range, even with a small-sized starter generator.
Implementation Method 1
this one-way clutch has a blocking direction, wherein torque transmission is possible in the blocking direction and torque transmission is disabled, at least temporarily or permanently, against the blocking direction
Implementation Method 2
the torque transmission device of the second drivetrain is designed as a speed-sensitive torque transmission device and preferably as a centrifugal clutch which allows torque transmission from the output shaft of the internal combustion engine to the output shaft of the electromechanical energy converter (closed state) above a predefinable first speed threshold and suppresses it below this first speed threshold (open state)
Data Source
AI summary
A motor vehicle drive apparatus includes a device configured to connect an internal combustion engine to an electromechanical energy converter, and first and second drive trains. The second drivetrain is arranged parallel to the first drivetrain in relation to torque transmission between the electromechanical energy converter and the internal combustion engine. The first drivetrain has a one-way clutch which is set up in such a manner that torque is transmittable via the first drivetrain from the electromechanical energy converter to the internal combustion engine during starting of the internal combustion engine. The second drivetrain has a speed-sensitive clutch which in a first state is open until a first speed threshold is reached, so that in the first state no torque is transmittable with the second drivetrain from the internal combustion engine to the electromechanical energy converter. The speed-sensitive clutch is closed from the crossing of this first speed threshold.