Motion Control Mechanism for Powertrain Oscillation Damping
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Solution Overview
Problem
Existing start-stop systems in vehicles fail to effectively reduce powertrain rigid body motion and crankshaft oscillations during engine start/stop cycles, leading to increased noise, vibration, and harshness (NVH) experienced by vehicle occupants.
Innovation Solution
A starting system comprising a starter motor and a motion control mechanism, where the starter motor's pinion gear selectively meshes with the engine's primary mass to initiate rotation, and the motion control mechanism's pinion gear, with an inertia mass and planetary gear set, dampens vibrations by applying additional inertia to the crankshaft, reducing oscillations and forces transmitted to the powertrain mounts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional starter motor is used to start the engine, then the engine can be started, but powertrain rigid body motion and crankshaft oscillations increase leading to higher NVH
Solution Approach 1:
A motion control mechanism with a mechanism pinion gear is introduced as an intermediary between the starter motor and the engine primary mass. This intermediary component absorbs and dampens the harmful oscillations and rigid body motions during engine starting, while still allowing the starter motor to effectively start the engine. The mechanism pinion gear engages with the primary mass and provides motion control during the starting transient.
Solution Approach 2:
The system changes the motion parameters of the primary mass during engine starting by introducing the motion control mechanism. This mechanism modifies the speed, acceleration, and oscillation characteristics of the primary mass rotation, thereby reducing NVH while maintaining reliable engine starting. The dual pinion gear arrangement allows for controlled parameter changes during the starting process.
2Loss of time
If the engine is started quickly to improve responsiveness, then engine start time is reduced, but NVH and harshness increase
Solution Approach 1:
The motion control mechanism applies periodic damping action during the engine starting process. The mechanism pinion gear engages and disengages in a controlled manner, applying periodic forces that dampen oscillations and reduce NVH while maintaining a reasonable engine start time. This periodic action allows the system to balance speed and comfort.
3Object-affected harmful factors
If a motion control mechanism is added to reduce NVH, then powertrain rigid body motion is reduced, but device complexity increases
Solution Approach 1:
The motion control mechanism is designed to perform multiple functions: it controls primary mass motion during starting, dampens oscillations, reduces NVH, and maintains engine starting capability. By consolidating these functions into a single integrated mechanism rather than separate systems, the patent reduces overall system complexity while achieving the desired NVH reduction.
4Device complexity
If the starter motor directly drives the primary mass, then the starting system is simple, but crankshaft oscillations and forces on powertrain mounts are high
Solution Approach 1:
The motion control mechanism acts as a counterbalancing element that offsets the harmful forces and oscillations generated during engine starting. The mechanism pinion gear provides a counteracting torque that reduces the net forces transmitted to the powertrain mounts, thereby reducing NVH while maintaining a relatively simple starting system structure.
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 significantly reduces powertrain and crankshaft oscillations, lowering NVH and improving the auto-start experience by slowing down the engine speed ramp and reducing forces on the vehicle's mounts, thereby enhancing the subjective feel during engine start/stop events.
Implementation Method 1
the motion control mechanism's pinion gear, with an inertia mass and planetary gear set, dampens vibrations by applying additional inertia to the crankshaft
Implementation Method 2
planetary gear set, dampens vibrations by applying additional inertia to the crankshaft
Implementation Method 3
The starter pinion gear is selectively rotatable about a first axis of rotation to cause the primary mass to rotate about a second axis of rotation
Data Source
AI summary
A starting system for an engine of a vehicle includes a starter motor and a motion control mechanism. The starter motor includes a starter pinion gear configured to selectively mesh with a primary mass of the engine. The starter pinion gear is selectively rotatable about a first axis of rotation to cause the primary mass to rotate about a second axis of rotation. The motion control mechanism includes a mechanism pinion gear that is configured to selectively mesh with the primary mass of the engine. The mechanism pinion gear is configured to rotate about a third axis of rotation in response to rotation of the primary mass about the secondary axis of rotation.