Hybrid Powertrain Mechanical Diode Engine Disconnect
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Solution Overview
Problem
Hybrid vehicles face challenges with bulky and slow wet disconnect clutches that are imprecise in engaging and disengaging rotating components, leading to suboptimal drivability and fuel efficiency.
Innovation Solution
A hybrid powertrain utilizing a mechanical clutch, such as a selectable one-way clutch or mechanical diode, that allows the IC engine to quickly and smoothly transition between providing motive force and freewheeling, enabling efficient engine braking and reducing the intrusiveness of transitions between powertrain operating states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wet disconnect clutches are used to separate rotating components, then the IC engine can be disconnected from the final drive unit, but the clutch becomes bulky and slow in engagement/disengagement
Solution Approach 1:
The patent replaces the wet disconnect clutch with a mechanical diode that uses a one-way clutch mechanism. This mechanical substitution eliminates the need for hydraulic fluid and complex friction-based engagement, providing instantaneous engagement and disengagement through pure mechanical action. The one-way clutch allows free rotation in one direction while locking in the opposite direction, achieving rapid response without the bulk and slowness of wet clutches.
Solution Approach 2:
The patent extracts the essential function of the wet disconnect clutch (separating rotating components) and implements it through a simplified mechanical diode structure. By removing the hydraulic fluid and friction-based engagement mechanisms, the design achieves the same disconnection capability with significantly reduced size and improved engagement speed.
2Reliability
If wet disconnect clutches are used to separate rotating components, then the IC engine can be disconnected from the final drive unit, but the clutch becomes bulky in size
Solution Approach 1:
The patent replaces the bulky wet disconnect clutch with a compact mechanical diode using a one-way clutch. This substitution eliminates the need for large hydraulic reservoirs, complex piston mechanisms, and friction surfaces, resulting in a significantly smaller component that provides the same engine disconnection capability.
Solution Approach 2:
The patent extracts the core disconnection function from the bulky wet clutch system and implements it through a minimal mechanical diode structure. By removing unnecessary hydraulic components and friction-based mechanisms, the design achieves the same reliability with much reduced volume.
3Reliability
If wet disconnect clutches are used to separate rotating components, then the IC engine can be disconnected from the final drive unit, but the engagement/disengagement becomes imprecise
Solution Approach 1:
The patent replaces the imprecise wet disconnect clutch with a mechanical diode that provides exact, binary engagement states. The one-way clutch mechanism ensures precise locking in one direction and complete freedom in the other, eliminating the gradual, imprecise engagement characteristic of friction-based wet clutches.
Solution Approach 2:
The patent extracts the disconnection function from the imprecise wet clutch system and implements it through a precise mechanical diode. By removing friction-based engagement mechanisms, the design achieves exact, repeatable engagement and disengagement states.
4Power
If the IC engine is used to provide rotational power, then motive force is supplied to the final drive unit, but frictional losses reduce fuel efficiency
Solution Approach 1:
The patent extracts the engine from the power transmission path when electric-only operation is desired, using the mechanical diode to completely disconnect the IC engine from the final drive unit. This eliminates parasitic frictional losses entirely during electric operation, significantly improving fuel efficiency.
Solution Approach 2:
The patent dynamically controls engine engagement based on operating conditions. The mechanical diode allows the engine to be disconnected during electric-only mode to eliminate frictional losses, while enabling immediate re-engagement when hybrid operation is required, optimizing fuel efficiency across different driving scenarios.
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 mechanical clutch improves drivability by allowing instantaneous freewheeling and quick re-engagement, enhancing fuel efficiency by minimizing IC engine usage and reducing frictional losses, particularly when combined with a powerful electric motor-generator.
Implementation Method 1
the selectable one-way clutch is configured to apply an engine braking force transmitted by the rotatable shaft to the rotational output
Data Source
AI summary
A hybrid vehicle and a powertrain for a hybrid vehicle are disclosed. A hybrid powertrain may include an internal combustion engine configured to provide rotational power to a rotatable shaft in a first rotational direction, and an electric motor-generator configured to selectively provide rotational power to a rotational output. The motor-generator may include a rotor fixed for rotation with the rotational output. The powertrain may further include an engine disconnect device comprising a mechanical clutch linking the rotatable shaft with the rotational output. More specifically, the rotatable shaft may drive the rotational output in the first rotational direction, and the rotational output may freewheel with respect to the rotatable shaft when rotating faster in the first rotational direction than the rotatable shaft.