Hybrid Vehicle Engine Brake Ring Gear Engagement
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Solution Overview
Problem
Hybrid vehicle transmissions face challenges in increasing electric-only torque capacity and regenerative braking capability, particularly at low speeds, due to limitations in engine operation range and packaging constraints within modern vehicle engines.
Innovation Solution
An electrically actuated one-way brake is integrated into the powertrain, selectively engaging the ring gear to hold the crankshaft against rotation, allowing for enhanced torque contribution from electric machines during both forward and reverse movements without increasing the transmission's axial length or requiring a hydraulic system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the transmission axial length is increased to accommodate additional braking components, then regenerative braking capability is improved, but packaging constraints are violated
Solution Approach 1:
The existing one-way brake designed for engine starting is made multi-functional by enabling it to provide both starting function and regenerative braking function. The brake engages with the ring gear on the flywheel, allowing it to constrain engine rotation during regenerative braking without requiring additional axial space, thus achieving universal functionality with existing components
Solution Approach 2:
The one-way brake mechanism serves itself by utilizing its existing structure and engagement mechanism to provide regenerative braking capability. The brake's natural one-way engagement characteristic is leveraged to allow motor-driven reverse rotation while preventing forward rotation during regenerative braking, eliminating the need for separate braking components
2Power
If a hydraulic braking system is added to enhance regenerative braking, then braking performance is improved, but device complexity increases
Solution Approach 1:
The hydraulic braking system is extracted and removed from the design. Instead of adding hydraulic components, the patent utilizes the existing electrically actuated one-way brake mechanism to provide regenerative braking function, eliminating the need for complex hydraulic systems while maintaining braking capability
Solution Approach 2:
The mechanical/hydraulic braking system is replaced with an electrically actuated brake system. The brake is controlled by an electric motor or actuator that engages and disengages the brake mechanism electronically, substituting complex hydraulic control with simpler electrical control mechanisms
3Force
If the engine operates outside its efficient speed range to provide torque at low vehicle speeds, then low-speed torque is improved, but fuel efficiency deteriorates
Solution Approach 1:
The one-way brake acts as an intermediary mechanism that enables the motor to directly drive the wheels at low speeds without requiring the engine to operate inefficiently. By constraining engine rotation while allowing motor-driven wheel rotation, the brake mediates between the motor's high-torque low-speed capability and the engine's efficient operating range
Solution Approach 2:
The power delivery function is segmented between the engine and motor. The engine handles efficient cruising at optimal speeds, while the motor provides low-speed torque assistance, with the one-way brake enabling independent motor operation. This segmentation allows each power source to operate in its efficient range
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
The solution enhances the vehicle's ability to provide increased electric-only torque and efficient regenerative braking, improving energy recovery and propulsion efficiency without altering the transmission's packaging or hydraulic system, thus addressing the limitations of existing hybrid vehicle technologies.
Implementation Method 1
The solenoid moves a pin in response to electric current such that the pin pushes the first pawl into the first engaged position
Data Source
AI summary
A powersplit hybrid powertrain includes an electrically actuated brake that selectively engages a ring gear attached to a flywheel. The ring gear may be, for example, a starter ring gear. Engagement of the brake while the engine is stopped permits use of both electric machines to provide torque to vehicle wheels, thereby increasing the electric torque capacity of the powertrain. The position of the brake is more space efficient than conventional input shaft brakes.