Hybrid Vehicle Engine Mount Compression Control
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Solution Overview
Problem
Hybrid electric vehicles operating at high engine torque and low speeds experience noise, vibration, and harshness (NVH) issues due to engine lugging conditions, which existing technologies have not effectively mitigated.
Innovation Solution
A vehicle system that includes an electric machine, an engine, an engine mount, and a controller, where the controller increases the engine speed beyond a base speed in response to engine mount compression to reduce engine lugging, utilizing a method that involves determining a minimum lugging speed and applying a lugging scale factor to adjust engine speed based on compression and environmental conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the hybrid electric vehicle operates at high engine torque and low speeds to maximize fuel economy, then fuel economy is improved, but NVH issues worsen due to engine lugging conditions
Solution Approach 1:
The system dynamically adjusts engine operating parameters (specifically engine speed) based on detected mount compression conditions. When vertical engine mounts are compressed, indicating potential lugging conditions, the controller increases engine speed to exit the lugging regime while maintaining the beneficial high torque operation for fuel economy.
Solution Approach 2:
The system employs feedback from sensors that detect engine mount compression status to continuously monitor engine operating conditions. This feedback loop enables the controller to respond in real-time to developing lugging conditions by adjusting engine speed, thereby mitigating NVH issues while preserving fuel-efficient operation.
2Productivity
If the engine operates at base speed corresponding to electric machine speed and engine power demand, then fuel economy is optimized, but engine lugging occurs causing vibrations and harshness
Solution Approach 1:
The system transitions from a static base speed operation to a dynamic speed adjustment strategy. The engine speed is no longer fixed at the base value but is dynamically modified based on real-time mount compression detection, allowing the engine to adapt its operating point to avoid lugging while maintaining overall fuel efficiency.
Solution Approach 2:
The system takes preliminary action by detecting mount compression before severe lugging symptoms manifest. By proactively increasing engine speed when compression is detected, the system prevents the full development of harmful vibrations and harshness rather than merely responding after problems occur.
3Object-affected harmful factors
If the controller increases engine speed to reduce engine lugging, then NVH performance is improved, but fuel economy may deteriorate
Solution Approach 1:
The system applies partial speed increase rather than full throttle application. Engine speed is increased just enough to exit the lugging regime and reduce NVH issues, rather than applying excessive power. This minimizes the additional fuel consumption while achieving the primary goal of reducing vibrations and harshness.
Solution Approach 2:
The speed adjustment is applied periodically or transiently only when mount compression conditions indicate lugging, rather than maintaining elevated speed continuously. This allows the engine to return to base speed when conditions improve, minimizing overall fuel penalty while providing NVH relief when needed.
Data Source
AI summary
A vehicle includes an electric machine, an engine, an engine mount, and a controller. The engine has a base speed that corresponds to a speed of the electric machine and an engine power demand. The engine mount is disposed between the engine and a vehicle structure such as a frame or unibody. The controller is configured to, in response to compression of the engine mount, increase an engine speed to a value that is greater than the base speed to reduce engine lugging.